chapter 8 other hardware components

8/8/2019 Chapter 8 Other Hardware Components

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• Printers

• Scanners

•

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Printers• A device that prints text or illustrations on paper. There are many different types of printers. In terms of the

technology utilized, printers fall into the following categories:

• Daisy‐Wheel: Similar to a ball‐head typewriter, this type of printer has a plastic or metal wheel on which the

shape of each character stands out in relief. A hammer presses the wheel against a ribbon, which in turn makes

an ink stain in the shape of the character on the paper. Daisy‐wheel printers produce letter‐quality print but

cannot print graphics.

• Dot‐Matrix: Creates characters by striking pins against an ink ribbon. Each pin makes a dot, and combinations

of dots form characters and illustrations.

• Ink‐ jet: Sprays ink at a sheet of paper. Ink‐ jet printers produce high‐quality text and graphics. laser: Uses the

same technology as copy machines. Laser printers produce very high quality text and graphics.

• LCD & LED : Similar to a laser printer, but uses liquid crystals or light‐emitting diodes rather than a laser to

produce an image on the drum.

• Line Printer (Page Printers): Contains a chain of characters or pins that print an entire line at one time. Line

printers are very fast, but produce low‐quality print.

• Thermal Printer: An inex ensive rinter that works b ushin heated ins a ainst heat‐sensitive a er.

Thermal printers are widely used in calculators and fax machines. Printers are also classified by the following

characteristics:3



Printers• Printers are also classified b the followin characteristics:

• Quality of type: The output produced by printers is said to be either letter quality (as good as a typewriter),

near letter quality , or draft quality .

– n y a sy‐w ee , n ‐ et, an aser pr nters pro uce etter‐qua ty type.

– Some dot‐matrix printers claim letter

‐quality print, but if you look closely, you can see the difference.

• Speed: Measured in characters per second (cps) or pages per minute (ppm), the speed of printers varies widely.

– Daisy‐wheel printers tend to be the slowest, printing about 30 cps. Line printers are fastest (up to 3,000 lines per minute).

– Dot‐matrix printers can print up to 500 cps, and laser printers range from about 4 to 20 text pages per minute.

• Impact or Non‐Impact: Impact printers include all printers that work by striking an ink ribbon. Daisy

‐wheel,

dot‐matrix, and line printers are impact printers. Non‐impact printers include laser printers and ink‐ jet

printers.

– The important difference between impact and non‐impact printers is that impact printers are much noisier.

• Graphics: Some printers (daisy‐wheel and line printers) can print only text. Other printers can print both text

and graphics.

• Fonts : Some rinters, notabl dot‐matrix rinters, are limited to one or a few fonts. In contrast, laser and ink‐

jet printers are capable of printing an almost unlimited variety of fonts. Daisy‐wheel printers can also print

different fonts, but you need to change the daisy wheel, making it difficult to mix fonts in the same document.4



Printers

Dais ‐Wheel Printer

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Dot Matrix Printer



Printers

Laser Printer

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Printer Communications Types

• When we say “communication types,” we’re actually talking about the hardware technologies involved

in getting the printed information from the computer to the printer. There are four major types: serial,

parallel, Universal Serial Bus (USB), and network.

Serial

• “, , .

line” like people at a movie theater, waiting to get in. Just as with modems, you must set the

communication parameters (baud, parity, start and stop bits) on both entities—in this case the

computer and its printer(s)—before communication can take place. Most of these cables are long.

Parallel

• When a printer uses parallel communication, it is receiving data eight bits at a time over eight separate

wires (one for each bit). Parallel communication is the most popular way of communicating from

computer to printer, mainly because it’s faster than serial.

‐ ‐

Centronics connector that connects to the printer. Most of the cables are shorter than 10 feet long.

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Printer Communications TypesUniversal Serial Bus (USB)

• It is actually the most popular interface for just about every peripheral. The convenience for printers is that it

has a higher transfer rate than either serial or parallel and it automatically recognizes new devices.

Network

•

Some of the newer printers (primarily laser and LED printers) have a special interface that allows them to behooked directly to a network. These printers have a network interface card (NIC) and ROM‐based software

that allow them to communicate with networks, servers, and workstations. The type of network interface used

on the printer depends on the type of network the printer is being attached to.

Infrared

• With the explosion of Personal Digital Assistants (PDAs), the need grew for printing under the constraints they

provide. The biggest hurdle faced by PDA owners who need to print is the lack of any kind of universal

interface. Most interfaces were too big and bulky to be used on handheld computers like PDAs.

• The solution was to incorporate the standardized technology used on some remote controls: infrared

transmissions. Infrared transmissions are simply wireless transmissions that use radiation in the infrared range

of the electromagnetic spectrum. Many laser printers (and some computers) come with infrared

transmitter/receivers (transceivers) so that they can communicate with the infrared ports on many handhelds.

s a ows t e user o a , an e , or aptop to pr nt to t at pr nter y po nt ng t e ev ce at t e pr nter

and initiating the print process.

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Print Media

• The print media is what you put through the printer to print on. There are two major types of print

media: paper and transparencies. Of the two types, paper is by far the most commonly used.

Paper• Aspects of paper that can be measured

– Quality of the paper.

–

Basis Weight

– Caliper (or thickness) of an individual sheet of paper.

Transparencies

• Transparencies are still used for presentations made with overhead projectors, even with the explosion

of programs like PowerPoint and peripherals like LCD computer displays, both of which let you show a

’ .

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Print Consumables

• Besides print media, there are other things in the printer that run out and need to be replenished

(refill). These items are the print consumables. Most consumables are used to form the images on the

print media. There are two main types of consumables in printers today: INK and TONER. Toner is used

primarily in laser printers. Most other printers use ink.

Ink

• Ink is a liquid that is used to “stain” the paper. There are several different colors of ink used in printers,

. ‐ ‐

ink, but with different methods.

Toner

• The final type of consumable is toner. Each model of laser printer uses a specific toner cartridge. The

different types of toner cartridges were covered in the discussions of the different types of printers. All

we would add here is to check the printer’s manual to see which toner cartridge it needs.

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Scanners• Resolution: The denser the bit ma the hi her the resolution. T icall scanners su ort resolutions of from

72 to 600 dpi.

• Bit Depth: The number of bits used to represent each pixel. The greater the bit depth, the more colors or

graysca es can e represen e . or examp e, a ‐ co or scanner can represen o e power .

million) colors. Note, however, that a large color range is useless if the CCD arrays are capable of detecting only

a small number of distinct colors.

• Size And Shape: Some scanners are small hand‐held devices that you move across the paper. These hand‐held

scanners are often called half ‐ page scanners because they can only scan 2 to 5 inches at a time. Hand ‐held

scanners are adequate for small pictures and photos, but they are difficult to use if you need to scan an entire

page of text or graphics. Larger scanners include machines into which you can feed sheets of paper. These are

called sheet ‐ fed scanners. Sheet‐fed scanners are excellent for loose sheets of paper, but they are unable to

handle bound documents.

• A second type of large scanner, called a flatbed scanner , is like a photocopy machine. It consists of a board on

which you lay books, magazines, and other documents that you want to scan.

• ver ea scanners a so ca e copy oar scanners oo somew a e over ea pro ec ors. ou p ace

documents face‐up on a scanning bed, and a small overhead tower moves across the page.

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What is Negative Scanners•

A negative scanner is, in a way, a bridge between the worlds of film and digital photography. Many longtime photographers are hesitant toabandon their wound film canisters and dark rooms for cold, lifeless storage cards and computers, but the benefits of going digital are

numerous. Digital cameras have become fairly affordable, and they eliminate the need to purchase roll after roll of film. Images can be

stored on a computer or on a CD; they can be printed out at any time; and they can be e ‐mailed to friends and family with the click of a

mouse.

• Skilled photographers, though, are still able to produce higher quality images using film cameras. Film cameras offer more control over all

the variables that go into taking a photograph, and digital cameras have struggled to match that quality for a comparable price. But

regardless of the type of camera, working on a computer has all but replaced working in a dark room. Thanks to the negative scanner,

p o ograp s a en on m can e eas y mpor e n o a compu er, w ere ey can e g a y man pu a e an processe .

• A negative scanner is piece of computer hardware that can read a film negative and reproduce it on the computer as a developed image.

The negative scanner helps conserve the time and energy required to develop photographs in a dark room, and it gives the photographer

more control over the way photos are processed than, say, the local supermarket. After placing the negative into the negative scanner, the

photographer can use a program such as Adobe Photoshop to import the images. One can then use the software to crop the photo, adjust

lighting and color or add any number of effects to the image. It can be done within seconds and it can always be undone, meaning fewer

headaches over minor mistakes.

• Like anything else, the negative scanner has been made available at many different pricing levels. There is the lower ‐priced, consumer‐

friendly type of negative scanner, which often can also process slides. These are particularly useful for people with boxes of old,

deteriorating negatives that can be preserved better digitally. There is also the higher‐end and much more expensive type of negative

scanner, which is more commonly used for professional publications like newspapers and magazines.

,

on negatives. Since just about all major newspapers have made the switch to digital photography and turned their dark rooms into storage

rooms, negative scanners are the only way to reprint any of these older photos in future issues.13



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